Product for the treatment of wastewaters and sewage

ABSTRACT

Biodegradable support carrying a mixture of non-pathogenic bacteria that synergistically cooperate in decomposing the organic pollutants present in toilet wastewaters and in sewage collection and processing tanks.

The present invention provides means for biodegrading the organicpollutants present in wastewaters and for preventing the formation ofagglomerates along the sewer pipes.

More specifically, the invention provides a biodegradable solid supportcarrying a mixture of non-pathogenic bacteria that synergisticallycooperate in decomposing the organic pollutants present in toiletwastewaters and in sewage collection and processing tanks, including theorganic agglomerates which lead to blockages along sewer pipes.

BACKGROUND OF THE INVENTION

The problem of effectively degrading the organic substances contained inwastewaters and sewage has been long felt. Besides to evidently causinghygienic problems, such organic substances are also responsible for theformation of encrustations and therefore of serious damages in time,along domestic pipelines to drainpipes.

Biological and chemical products are currently used to safeguard theintegrity and good state of pipelines to drainpipes; in many cases suchproducts may result either harmful to the user or scarcely effective ineliminating the substances responsible for pipe blockage and sewagesludge accumulation.

STATE OF THE ART

The patent application WO00/01621 discloses biological means forsanitary drainage of polluted effluents and/or maintenance of a sewerpipe system for evacuating said effluents, characterised in that itcomprises at least a biodegradable support, particularly bioactivetoilet paper loaded with a composition of saprophytic bacteria belongingto at least one of the species Bacillus subtilis, Rhodococcus rubica,Rhodococcus rubra, Pseudomonas putida, Pseudomonas putrefaciens.

DISCLOSURE OF THE INVENTION

The invention provides an optimised bacterial composition which provedsafe, non-pathogenic when contacted with either intact or laceratedhuman body tissues, particularly effective in decomposing the organicpollutants that are present in the wastewater collection and transportpipes, and which can be applied to a biodegradable solid support,especially toilet paper, maintaining unaltered biodegradation activityupon storage for long periods of time and under disparate environmentalconditions. The bacterial composition consists of five sporogenousstrains of the genus Bacillus, which synergistically cooperate in thebiodegradation of organic pollutants present in the wastewaters. Thebacteria, or preferably their spores, are deposited on a biodegradablesupport and become active upon contact with water, thereby initiatingthe process of biological degradation of the organic pollutants. Inparticular, the activated bacteria produce enzymes that penetrate indepth into the organic agglomerates present in the wastewater pipesand/or collection tanks, promoting their decomposition into carbondioxide and water. The bacteria mixture according to the invention hasdemonstrated a high synergistic biodegradation activity on wastewaterfrom toilet pipes, also preventing the formation of large agglomerateswhich lead to blockages along sewer pipes and considerably reducing theorganic pollutant content present in collection and processing tanks(trap tanks, septic tanks, Imhoff tanks, cesspools, seepage trenchesetc.).

Accordingly, in a first embodiment the invention is directed to aproduct for the biodegradation of the organic substances contained inwastewaters from toilets, pipes and in sewage collection tanks, saidproduct comprising a biodegradable solid support carrying a mixture ofbacterial strains of the genus Bacillus, species subtilis,licheniformis, megaterium, polymyxa and circulans. The bacterialstrains, preferably in the spore state, may be applied onto thebiodegradable support in a liquid medium, preferably in form of solutionor suspension in water optionally containing additives (e.g.stabilisers) and co-solvents. In a particularly preferred embodiment,the bacterial spores are used at a concentration of 10⁶ to 10⁹ CFU(colonies forming units) per ml. The bacterial mixtures have preferablythe following quantitative composition: B. subtilis from 20 to 30%, B.licheniformis from 10 to 20%, B. megaterium from 10 to 20%, B. polymyxafrom 20 to 30%, and B. circulans from 10 to 20%. Any bacterial strain ofthe indicated species may be used in accordance with the invention,irrespective of its origin or natural source.

The biodegradable support is preferably made of pure cellulose or of acellulose derivative, e.g. recycled paper, de-inked paper, syntheticmaterials or non-woven fabrics; examples of cellulose orcellulose-derived products that can be used according to the inventioninclude handkerchiefs, serviettes, napkins, diapers, sanitary towels,absorbing papers and preferably toilet paper. When the product is inform of toilet paper, a liquid culture of bacteria can be applied to atleast one surface thereof by a process of spraying or coating, asdescribed in further detail below. The same process can be used forother supports, if necessary with modifications depending on the shape,thickness, tensile strength, breakage resistance, loading capacity andother structural and mechanical characteristics of the support. Anyoneskilled in the art will be able to determine the better conditionsdepending on the particular support and on the apparatus used for itsmanufacturing.

In addition to the bacteria, the biodegradable support may containfurther ingredients including softening agents, surface-active agents,perfumes, dyes.

In a further embodiment, the invention relates to the use of abiodegradable solid support carrying the bacteria mixture describedabove, for degrading the organic substances contained in wastewaters andsewage, and for eliminating the organic agglomerates and the unpleasantodours that form in the wastewater pipes and collection tanks.

The following examples illustrate the invention in greater detail.

EXAMPLE 1 Preparation of the Bacterial Composition

The bacterial composition (hereafter indicated as B.A.T.P.L1700S) is anaqueous suspension of spores of the following bacterial strains:

-   -   Bacillus subtilis (ATCC 6051), Gram-positive, mesophilic,        aerobic, produces endospores that are highly resistant even in        environments which are not very favourable to biological growth,        and produces a large variety of enzymes (protease and        beta-glucanase) specific for sugars and starches.    -   Bacillus Licheniformis (ATCC 12713), Gram-positive, mesophilic,        anaerobic, sporogenous, produces protease, amylase and lipase,        specific for breaking down fats, resistant in environments with        high concentrations of NaCl (up to 7%), denitrifying activity in        anaerobic conditions, also grows at high temperatures (up to 50°        C.).    -   Bacillus Megaterium (ATCC 14581), Gram-positive, mesophilic,        aerobic, sporogenous, produces α,β-amylase enzymes specific for        breaking down starches, protease for casein, resistant in        environments with high concentrations of NaCl (up to 7%).    -   Bacillus Polymyxa (ATCC 842) Gram-positive, mesophilic,        anaerobic, sporogenous, produces cellulase and hemicellulase        specific for breaking down cellulose and paper, nitrifying        activity.    -   Bacillus Circulans (ATCC 9500) Gram-positive, mesophilic,        facultative anaerobic, sporogenous, produces protease, chitinase        and pectinase, specific enzymes for breaking down plant        derivatives, fibres and paper, resistant to high temperatures        (up to 50° C.).

ATCC=American Type Culture Collection, Manassas, Va., USA

The biological product has the following characteristics:

APPEARANCE: cloudy liquid

COLOUR: straw yellow

pH: 8.2-8.8

DENSITY: 1000-1025 g/cm³

STABILISER: propylene glycol

CFU/ml: 100×10⁷

SAFETY: there is no risk, even in the event of improper use, such asswallowing, handling or contact, even with the genitals.

The bacteria count of 1 billion per g was specifically chosen to allowan appropriate application of product to each cm² of toilet paper; thiscount ensures a correct input of the bacterial pool into the sewerswithout damaging the toilet paper during manufacture of the roll.

The product is used in liquid form with or without added enzymes,perfumed, in aqueous emulsion or solvent.

EXAMPLE 2 Study of the Efficacy of the Individual Bacterial Strains in aSewer System

The purpose of this study was to demonstrate that the biodegradationactivity of the micro-organisms contained in the biological productB.A.T.P.L1700S is greater than that obtained by micro-organismsbelonging to each type of bacterial strain taken separately. The testwas conducted in a simulated sewer system by observing the variation inCOD (Chemical Oxygen Demand) determined in a sample of water containingchemically oxidisable organic substances. The tests were conducted inparallel with a simulated sewer system with no biological treatment,subjected to the same experimental conditions.

The determination of the COD value in the wastewater provides aquantitative measurement of the presence of pollutant organic compounds.The reduction in COD caused by the micro-organisms is therefore a goodindicator of the efficacy of the product used.

Procedure:

3.5 litres of water containing 3 g of sugar (source of carbon) and 3 gof nutrient compound (source of N.P.K.: 12:5:10) was prepared.

The solution was divided into seven 0.5 litre containers (A, B, etc.).

The COD of the solution was measured prior to treatment (after decantingfor 1 h). The value found corresponds to the basal COD value for eachsample.

The samples were kept under agitation (at very low speed) and at aconstant temperature of 35° C. After agitation a sheet of toilet paperwas added to each container.

Each sample was treated every day for 15 days as follows:

10 ml of water in container A

10 ml of Bacillus Subtilis 20×10⁶ in container B

10 ml of Bacillus Licheniformis 20×10⁶ in container C

10 ml of Bacillus Megaterium 20×10⁶ in container D

10 ml of Bacillus Polymyxa 20×10⁶ in container E

10 ml of Bacillus Circulans 20×10⁶ in container F

1 ml of B.A.T.P.L1700S 1×10⁹ in container G.

After treatment, each sample was subjected to agitation at very lowspeed for 10 min/day. Finally, a sheet of toilet paper was added.

The COD measurement and the treatment (T) were performed according tothe following pattern:

day COD T 0 x 1 x 2 x 3 x x 4 x 5 x 6 x x 7 x 8 x 9 x x 10 x 11 x 12 x x13 x 14 x 15 x x

The sample for COD determination was taken after leaving the solutionsto stand for 1 h (without agitation). The sample was taken approx. 1 cmfrom the base of the container, taking care to avoid the solid componentdeposited and/or in suspension.

Results

TABLE a COD values expressed in mg/litre A B C D E F G day watersubtilis licheniformis megaterium polymyxa circulans BATPL1700S 0 18501850 1850 1850 1850 1850 1850 3 1884 1721 2013 1699 1818 2005 1780 62405 1905 2288 2210 2153 2364 1106 9 3047 1899 2894 2573 2589 2792 88412    3500(**) 2157 2802 2781 2422 2807 653 15    3500(**) 2100 27912664 2360 2640 488 (**)The maximum COD value detectable with the methodused is 3500; for samples which fell outside this limit, the value of3500 mg/L was conventionally indicated.

TABLE b % reduction in pollutant content after treatment B C D E F G daysubtilis licheniformis megaterium polymyxa circulans BATPL1700S 0 0 0 00 0 0 3 9 0 10 4 0 6 6 12 5 8 10 2 54 9 10 5 6 15 8 71 12 18 13 15 14 1481 15 25 15 10 15 13 86

Remarks

To demonstrate that biodegradation of the micro-organisms contained inB.A.T.P.L1700S is more effective than that of the individual bacterialstrains, 7 identical simulated sewer systems with a known COD (basalvalue of 1850 mg/litre) were prepared.

A sheet of toilet paper was added to each sample for 15 consecutive daysand the treatment described above under “procedure” was performed. Thecorresponding COD was measured every 3 days.

The percentage reductions in pollutant content for each treated samplecompared with sample A (untreated=water) were calculated on the basis ofthe results obtained (Table a). The graph of FIG. 1 shows the totalpercentage reductions by the 5 strains (white bar) and the correspondingreduction by B.A.T.P.L1700S (grey bar). Table a) indicates that:

1) in a sewer system, in the absence of biological treatment (sample A),the COD tends to increase with time, ie. the concentration of chemicallyoxidisable organic substances (pollutants) increases.

2) in a sewer system, the presence of a biological treatment reduces theCOD over time, ie. the concentration of chemically oxidisable organicsubstances (pollutants) is reduced by the degradation action of themicro-organisms. The different COD reduction percentages found,indicating different breakdown activities, are evidently dependent onthe specificity of the enzymes produced by the bacteria. Thisspecificity distinguishes each strain selected, and also depends on themore or less favourable environmental conditions of the sewer system.Under our conditions the most resistant strains, B. Subtilis and B.Polymyxa, demonstrated a more constant activity over time, which wassuperior in percentage terms to that of the other strains.

3) when treated with B.A.T.P.L1700S, the COD of the system decreasessignificantly over time due to the biodegradation activity of themicro-organisms belonging to all 5 strains contained in the product; inthe presence of organic substances and favourable environmentalconditions these micro-organisms become active, feed and reproduce,reducing the pollutant levels from 1850 on the first day to 488 on thelast, namely a reduction of 86%.

The graph of FIG. 1 clearly shows that the biodegradation activityB.A.T.P.L1700S in the sewer system is superior to the sum of theactivities of the 5 strains taken individually.

EXAMPLE 3 Study of the Efficacy of B.A.T.P.L1700S in a Sewer System

The purpose of this study was to establish the efficacy ofbiodegradation of the micro-organisms contained in B.A.T.P.L1700S in asimulated sewer system, by observing the variations in COD (ChemicalOxygen Demand) determined in a sample of water containing chemicallyoxidisable organic substances. This efficacy was compared with that of aproduct already on the market, namely WC Net Fosse Biologiche, abacteria-based powder with a CFU count of 200 million per g, andcompared with a system without biological treatment.

The determination of the COD value in the wastewater provides aquantitative measurement of the presence of pollutant organic compounds.The reduction in COD caused by the micro-organisms is therefore a goodindicator of the efficacy of the product used.

Procedure:

1 litre of water containing 1 g of sugar (source of carbon) and 1 g ofnutrient compound (source of N.P.K.: 12:5:10) was prepared.

The solution was divided between three 0.5 litre containers (A, B andC).

Prior to treatment, the COD of the solution was measured (afterdecanting for 1 h); the value found corresponds to the basal COD valuefor each sample.

The 3 samples were maintained under agitation (at a very low speed) andat a constant temperature of 35° C.

sample B: treated with 0.21 μL(*) of B.A.T.P.L1700S on ¼ sheet of toiletpaper (approx. 25 cm²).

Sample C: treated every 5 days with 5 ml of a solution consisting of 125mg of WC Net in 500 ml, prepared according to the manufacturer'sinstructions.

1 sheet of paper with B.A.T.P.L1700S was inserted in sample B, and 1sheet of untreated paper in sample A and sample C, every day for 15consecutive days.

Sample A: treated every 5 days with 5 ml water.

After treatment, each sample was agitated at very low speed for 10min/day.

The COD measurement, the addition of the toilet paper (F) and thetreatment (T) were performed according to the following pattern:

A = water B = BATPL1700S C = WC Net day COD F T COD F T COD F T 0 x x xx x x 1 x x x x 2 x x x x 3 x x x x x x x 4 x x x x 5 x x x x x x 6 x xx x x x x 7 x x x x 8 x x x x 9 x x x x x x x 10 x x x x x x PHOTO 11 xx x x 12 x x x x x x x 13 x x x x 14 x x x x 15 x x x x x x x x x PHOTO

The sample for the determination of COD was taken after leaving thesolutions to stand for 1 h (without agitation); the sample was taken onthe surface, at a depth of approx. 1 cm, avoiding the bacterialcomponent and solids in suspension.

(*) dose equal to 5 g/60 m² of toilet paper

Results

TABLE c day A = water B = BATPL1700S C = WC Net 0 950 950  950 3 13401280 2010 6 1410 1390 1980 9 3500 765 3027 (**) 12 2490 498 3500 (**) 152880 444 3108 (**) The maximum COD value obtainable with the method usedis 3500; for samples exceeding this limit, the value of 3500 mg/l wasconventionally indicated.

Remarks

To demonstrate the efficacy of biodegradation of the micro-organismscontained in B.A.T.P.L1700S and compare it with that of a known product,3 identical simulated sewer systems with a known COD were prepared.

A sheet of toilet paper was added to each sample for 15 consecutivedays: untreated for samples A and C, treated with B.A.T.P.L1700S forsample B, as described under “Procedure”. Samples A and C were treatedevery 5 days with water and “WC Net Fosse Biologiche” respectively atthe dose stated above. The corresponding COD was measured every 3 days.

The results obtained were recorded on the graph of FIG. 2; the line thatstatistically interpolates all the values obtained (“trend line”), wascalculated for each set of data corresponding to each sample. The graphindicates that:

1) In a sewer system, in the absence of biological treatment (sample A),the COD tends to increase with time, ie. the concentration of chemicallyoxidisable organic substances (pollutants) increases.

2) The treatment performed with “WC Net Fosse Biologiche” provedineffective; paradoxically, a trend line of higher COD values wasobserved in sample A.

3) In the case of treatment with B.A.T.P.L1700S, the COD of the systemdeclined over time due to the biodegradation activity of themicro-organisms contained in the product; in the presence of organicsubstances and favourable environmental conditions these micro-organismsbecome active, feed and reproduce, reducing the pollutant levels.

Macroscopic observation of the 3 samples with the naked eye alsoconfirmed the results of the COD measurement.

Each sample was photographed on the 10th day (FIG. 3).

Sample A: cloudy supernatant liquid with particulate matter deposited onthe base and intact sheets of paper still clearly evident and notdecomposed.

Sample B: supernatant liquid clearer than in A, homogenous particulatematter deposited on the base, paper is decomposed.

Sample C: cloudy liquid, floating particulate part containing the sheetsof intact paper, still clearly evident, and mould formation.

Photos taken on the 15th day (FIG. 4):

Sample A: Supernatant liquid cloudy, large deposits on the base andtoilet paper still clearly distinguishable, mould formation.

Sample B: Homogenous supernatant liquid, toilet paper broken down anddissolved, thick but homogenous deposits on the base, no formation ofmould and/or

Sample C: supernatant liquid cloudy, large deposits on the base andtoilet paper still clearly distinguishable, mould formation.

EXAMPLE 4 Evaluation of the Optimum cfu/(Cm² of Paper) Ratio

Domestic Use

On the assumption that the average weekly consumption of toilet paper bya family of four is approx. 5 rolls, and that each roll is approx. 19 mlong and 10 cm wide, approx. 9.5 m² (1900 cm×10 cm×5 rolls=95000 cm²) oftoilet paper a week is discharged into the sewers.

The correct load of bacterial strains into the sewer pipes of such afamily has been calculated at 2,000 million CFU/week to activate andmaintain the process of decomposition of the organic substances,eliminate unpleasant odours and fully dissolve the cellulose particles.

The amount obtained, namely 2,000 million CFU, equal to 2 g of theB.A.T.P.L1700S product, must be deposited on 9.5 m² of toilet paper.

Use in Communities

On the assumption that the average weekly toilet paper consumption of ahotel with 20 double rooms, namely 40 guests, is approx. 40 rolls, andthat each roll is approx. 19 m long and 10 cm wide, approx. 76 m² (190cm×10 cm×40 rolls=760000 cm²) of toilet paper a week is discharged intothe sewers.

The correct load of bacterial strains into the sewer pipes of such ahotel has been calculated at 25,000 million CFU/week to activate andmaintain the process of decomposition of the organic substances,eliminate unpleasant odours and fully dissolve the cellulose particles.

The amount obtained, namely 25,000 million CFU, equal to 25 g of theB.A.T.P.L1700S product invented, must be deposited on 76 m² of toiletpaper.

EXAMPLE 5 Application of Bacteria to Paper

The product can be applied to toilet paper by two methods: spraying orcoating.

The spraying apparatus can be installed in the converting unit (wherethe finished paper is bonded, cut and packaged) or the final part of thepaper mill, where the finished paper is rewound and sent to theconverting unit for subsequent processing.

The spraying application in the converting unit takes place at the“paper passage point” before “embossing and gluing”, “DESL” or“tip-to-tip”, depending on the type of processing selected. The plant issituated immediately before the sheet bonding process.

In the paper mill the apparatus is positioned at the point preceding thesheet bonding stage and after the roll rewinding stage, called the “bigroll” stage.

The spray application system comprises nozzles that spray (according tothe speed of the machine) a quantity of product sufficient to cover theentire length of the final roll.

The nozzles operate by collision of 2 converging jets, one of compressedair and the other of bacterial product, to a create a jet consisting ofparticles with an average diameter of under 10 microns. The systemincludes a storage tank for the bacterial product under agitation, afeed pump, 1-5 atomiser nozzles, depending on the aperture and speed ofthe machine (converting unit or rewinder), a screen that conveys the jetinto the two layers, management software, and a system that controls thequantity delivered on the basis of the number of machine revolutions(acceleration or slowing of the speed of the machine).

If the spray method is used, our biological product can be combined withthe dose of softener following a biocompatibility test.

In the coating application system (the rotogravure type of flexographicsystem) the product is taken up by a “honeycomb” steel roller withmicroperforations which passes over a subsequent roller, and distributesthe bacterial product on the paper. This type of application can be usedin the converting unit at the final stage in the paper mill, or at theplace where the paper is rewound.

If the coating (flexographic) method is used, the bacteria can becombined with the sheet-bonding adhesive, following a biocompatibilitytest.

1. Product for the biodegradation of organic substances contained in thewastewaters from toilets, pipes and in sewage collection tanks, whichcomprises a biodegradable solid support carrying a mixture of bacterialstrains of the genus Bacillus, species subtilis, licheniformis,megaterium, polymyxa and circulans.
 2. A product according to claim 1,wherein the biodegradable solid support is essentially made of celluloseor of a cellulose-derivative.
 3. A product according to claim 2, whereinthe solid support is essentially made of recycled paper, de-inked paper,synthetic materials or non-woven fabrics.
 4. A product according toclaims 1, wherein the solid support is selected from handkerchiefs,serviettes, napkins, diapers, sanitary towels, absorbing papers.
 5. Aproduct according to claim 1, wherein the solid support is toilet paper.6. A product according to claim 1, wherein the bacterial strains are inin the spore state.
 7. A product according to claim 1, wherein the solidsupport contains softening agents, surface-active agents, perfumesand/or dyes.
 8. A product according to claim 1, which is a toilet papercarrying on at least one surface the bacterial strains.
 9. A process forthe manufacturing of the product of claim 1, which comprises applyingthe bacterial strains to the biodegradable solid support by spraying orcoating.
 10. A process according to claim 9, wherein the bacterialstrains are in the form of a solution or suspension in water optionallycontaining additives and co-solvents.
 11. A process according to claim10, wherein the concentration of bacterial strains ranges from 10⁶ to10⁹ colony-forming units (CFU) per ml.
 12. The use of a biodegradablesolid support carrying a mixture of bacterial strains of the genusBacillus, species subtilis, licheniformis, megaterium, polymyxa andcirculans, for degrading the organic substances contained in wastewatersand sewage and for eliminating the organic agglomerates and theunpleasant odours that form in the wastewater pipes and collectiontanks.